chev 3500 with 5.0L sluggish and no power

Anonymous-0 · Dec 23, 2012

I just bought a 1995 chev 3500 4x4 cab and chassis with a 5.0L gas engine 4 speed auto. with 154000 kms with an 8ft western plow.Bought it from the small town next to me. The mechanic said it sat for abouit 6 months off duty because the new truck came in early. He said it ran ok before it was parked but had a soft brake pedal.We were only allowed to start it in the yard before we bid on it, because of the soft brake pedal. I had it towed home and went to move it around the yard it backfired through the intake and stalled ,it did this a few times. went and got some new gas and inhjector cleaner and put it in it. starts right up every time. wasnt planning on useing it untill I had it looked at but my plow truck through a ujoint on an axle so.I grabbbed the new truck and started to plow.It has no power and wants to chug and fart ,when you apply the pedal.If you find the sweet spot with the throttle it will smooth out but still has no power it will die off under load. It stalls constantly but starts right up again. when you start and rev it up it feels like it is plugged up and a few revs and ease on the throttle it will smooth out.If you push it hard it will start to smell like burnt paint.When you start to move ahead or back it chuggs and then if you feather the throttle it will smooth out untill gets back under load and then it starts to chugg again. the exhaust sounds like it is not releaseing the exhaust. Any suggestions??

Anonymous-0 · Dec 23, 2012

Plugged catalytic converter?

Royse · Dec 23, 2012

Unhook the exhaust before the catalytic converter and see it that helps.
If it does, converter may be plugged.

cleo kain · Dec 23, 2012

Sounds like clogged catalitic convertor. Does it have one ?

ShadetreeRet · Dec 23, 2012

Survey says---catalytic converter. I had a Chrysler a few years ago that started losing power on acceleration and if you set in neutral and stepped on the throttle, it sounded like you were trying to push a tornado through a keyhole. Due to the converter being stopped up it was leaking around the exhaust manifold and exhaust pipe. It was one of those that had the little springs and bolts that held it together at that point.

Anonymous-0 · Dec 23, 2012

I was thinking that way. But why will it come and go when you feather the throttle and hit the sweet spot? I know it still loses power when you get to a load.It runs so nice for while and dies out again.

Royse · Dec 23, 2012

If it's a plugged cat, it will let some air through, just not enough.
So at the right volume of air flow it will work Ok.
Don't run out and buy a new cat, just unhook it and see if it helps.
If it does or does not, then you have a little more information to go on.

Anonymous-0 · Dec 23, 2012

Not an answer to your question, but didn't know they put a 5.0 in a 4wd one-ton pickup. Would that be a 305? I would think that would be terribly underpowered on a good day.

I love Chevys.

Glenn

Royse · Dec 23, 2012

(quoted from post at 01:07:30 12/24/12)I would think that would be terribly underpowered on a good day.

I would think you are correct, but it should still run right.

Stephen Newell · Dec 23, 2012

I agree it sounds like a plugged exhause If it is you can disconnect the exhaust at the engine and see if that is the problem. If that isn't it, I have a 95 Chev van with the same engine. Except for the backfiring a lot of what your 4x4 is doing mine was doing when it needed a new ignition module.

CenTex Farmall · Dec 24, 2012

If pulling the cat doesn't make much difference, replace the fuel filter and if that doesn't help then check the fuel pressure for a possible bad fuel pump.

MarkB_MI · Dec 24, 2012

Start with the fuel filter. And if it's still on its original fuel pump it's due for replacement.

oliver power · Dec 24, 2012

My same thoughts Glen.........

S.Crum · Dec 24, 2012

My 95' Chevy 1500 is acting in a similar way. This truck sat for about 6 months before I bought it. It has the 5.7 TBI engine. Starts and runs good and drives up to speed ok. BUT when you try to take off hard and especially under load, it dies out (doesn't stall) and takes what seems like forever to build up to speed. Gas mileage is about half as good as the F-150 it replaced. This has 140,000 miles on the clock. I'm thinking putting Vinnie's scanner on it to see if the O2 sensor is acting funny, I'm going to pick up a new fuel filter today, and if the filter and possably the O2 sensor don't help then I'll go after the CAT. Be interesting to see how these issues shake out. RVS Please post your results, thanks

ASEguy · Dec 24, 2012

To check for restricted exhaust, which it may be, hook a vacuum guage to a manifold signal and increase engine speed in park to approximately 2,000 to 2,500 RPM's and watch the guage. If the exhaust is restricted, it will slowly decrease vacuum relative to the blockage. If it's not restricted the vacuum will "top out" and stay there. If it is restricted, make sure you hit the exhaust other places to see if the material, usually catalyst, travelled downstream. Gerard

Anonymous-0 · Dec 24, 2012

I did change the fuel filter at the beginning made no difference.Put clean fuel with an additive to clean up old fuel. burn that tank of fuel and now on new gas ,same thing. Will try the cat today, and let you know. thanks meveryone for your help. I will keep you updated.

Anonymous-0 · Dec 24, 2012

I am going by what the mechanic told me as for the size of the motor because the tag under the hood is missing. Going to the dealler with the VIN number to verify the engine size. I will let you know. I can tell the difference between underpowered and no power, This thing just doesn't have it right now.

Allan in NE · Dec 24, 2012

Ya don't have a load of water in yer fuel do ya?

Allan

S.Crum · Dec 24, 2012

I'm betting you'll find you have a 5.7 engine (with no power) like mine. Unless of course it was special ordered or somebody swapped engines.
The 5.7 or 350 if you will, is a powerhouse engine when running correctly, Not quite a 427 or 454, but they can do about anything a K-3500 chassis can hack.
The 305 or 5.0 is nothing more than a 350 with smaller holes in the block. Remember when Chevy reduced the 327 to a 307? Same deal. Although 300+- cubic inches seems to be the magic number for good all around driveability V-8 engines.

buickanddeere · Dec 24, 2012

The sweet spot of the throttle is the clue. The cat if clogged is not the primary problem.
Replace the throttle position sensor and O2 sensor.
I can't believe the check engine light isn't illuminated?
As previously stated fuel pressure should be measured.
Last set of proper gapped plugs, new solid core/spiral wound wires, no quality cap and quality rotor.
Wife's old Jimmy 4.3 on a regular basis used to plug the injectors and produce a lousy spray pattern.
The old classic failed intake gasket could be an issue too.

buickanddeere · Dec 24, 2012

Is there a mass airflow sensor on those? They are noted for getting dirty and out of calibration.
I have revived some MAFS temporarily with a good blast of aerosol electrical cleaner or ether.
Do not touch the internal wires.

johndeere720diesel · Dec 24, 2012

We had a suburban acted same way first would be fuel filter after checking the cat also check the cap and rotor ours chewed them up every six months it would need a new one after the fuel filter and cap and rotor we had to change the fuel pump it ran great

GordoSD · Dec 24, 2012

I bought a new 79 4spd El Camino with the 305 and pretty low number rear end. (3:20 or so)I lived at the bottom of a fairly steep hill in San Diego. I had to back up the hill to get to the top.
If I went the other way, went around the cul de sac and got some speed up I could make it in low gear. What a piece of..work.
And it still got only 18 mpg.

Hay_Man · Dec 24, 2012

I had a gutless 350 in a 78 GMC "Heavy Half" pick-up truck. At 125K miles I pulled the engine, dismantled it, Machine shop steamed it out, verified cylinders in standard, block was 4 bolt mains, heads had the big valves and stems (2.02s?), push rods were big ones too. Re-worked the heads, milled .010 to true 'um up. Went back with 10.5-1 pistons, shimmed the valve springs, new cam and lifters from Chet Hebert, high volume oil pump, Carter Thermo-Quad Carb, headers, 2" exhaust, new style electric transmission with locking torque converter. Made one strong truck out of it and won a few races, too. Got decent mileage, if I could keep my foot out of it...

chev 3500 with 5.0L sluggish and no power

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